Method and Apparatus for Vascular Tissue Sealing with Active Cooling of Jaws at the End of the Sealing Cycle

ABSTRACT

An end effector assembly for use with an electrosurgical instrument is provided. The end effector assembly has a first jaw member and a second jaw member. The second jaw member includes a channel defined therein and coupled to a cooling agent source and at least one venting port defined therein and fluidly coupled to the channel. During active cooling of the second jaw member, the cooling agent source is configured to supply a cooling agent to the channel.

BACKGROUND

1. Technical Field

The present disclosure relates to electrosurgical instruments used for open and endoscopic surgical procedures for sealing or fusing tissue. More particularly, the present disclosure relates to a bipolar forceps for sealing vessels, vascular tissues and soft tissues having an electrode sealing assembly which is designed to limit and/or reduce thermal spread to adjacent tissue structures by rapid cooling.

2. Background of the Related Art

Open or endoscopic electrosurgical forceps utilize both mechanical clamping action and electrical energy to effect hemostasis. The electrode of each opposing jaw member is charged to a different electric potential such that when the jaw members grasp tissue, electrical energy can be selectively transferred through the tissue. A surgeon can cauterize, coagulate/desiccate and/or simply reduce or slow bleeding, by controlling the intensity, frequency and duration of the electrosurgical energy applied between the electrodes and through the tissue.

Certain surgical procedures require more than simply cauterizing tissue and rely on the combination of clamping pressure, electrosurgical energy and gap distance to “seal” tissue, vessels and certain vascular bundles. More particularly, vessel sealing or tissue sealing utilizes a unique combination of radiofrequency energy, clamping pressure and precise control of gap distance (i.e., distance between opposing jaw members when closed about tissue) to effectively seal or fuse tissue between two opposing jaw members or sealing plates. Vessel or tissue sealing is more than “cauterization”, which involves the use of heat to destroy tissue (also called “diathermy” or “electrodiathermy”). Vessel sealing is also more than “coagulation”, which is the process of desiccating tissue wherein the tissue cells are ruptured and dried. “Vessel sealing” is defined as the process of liquefying the collagen, elastin and ground substances in the tissue so that the tissue reforms into a fused mass with significantly-reduced demarcation between the opposing tissue structures.

Using electrosurgical instruments to seal tissue may result in some degree of so-called “thermal spread” across adjacent tissue structures. “Thermal spread” refers generally to the heat transfer traveling along the periphery of the electrically conductive surfaces. This can also be termed “collateral damage” to adjacent tissue. As can be appreciated, reducing the thermal spread during an electrical procedure reduces the likelihood of unintentional or undesirable collateral damage to surrounding tissue structures which are adjacent to an intended treatment site. Reducing the collateral damage to surrounding tissue or maintaining the viability of surrounding tissue after the sealing process is known to promote tissue healing and decrease overall healing time by stimulating/improving healing response.

Controlling tissue cooling may also reduce adhesion or buildup of tissue on the electrodes and also assist during the formation of the tissue seal, e.g., cross-linking or other chemical bonding, during the reformation or renaturation of collagen. In existing sealing devices this cooling takes place in a natural-passive-way (due to heat exchange with the environment) after energy application is stopped. The cooling rate in this case is determined by thermal properties of the tissue and the jaw members and by the arrangement of heat exchange between jaws and the environment.

SUMMARY

In an embodiment of the present disclosure, an end effector assembly is provided. The end effector assembly has a first jaw member and a second jaw member. The second jaw member includes a channel defined therein and fluidly coupled to a cooling agent source and at least one venting port defined therein and fluidly coupled to the channel. During active cooling of the second jaw member, the cooling agent source is configured to supply a cooling agent to the channel.

In another embodiment of the present disclosure, an electrosurgical instrument for sealing tissue is provided. The electrosurgical instrument may include a housing having a cooling agent source and a valve configured to control the supply of cooling agent from the cooling agent source. The instrument may also include an end effector assembly having a first jaw member and a second jaw member. The second jaw member includes a channel defined therein and fluidly coupled to a cooling agent source and at least one venting port defined therein and fluidly coupled to the channel. During active cooling of the second jaw member, the cooling agent source is configured to supply a cooling agent to the channel.

The second jaw member may include a temperature sensor configured to detect a temperature of the second jaw member. The detected temperature may be used to determine a duration of time that the cooling agent source supplies the cooling agent. Alternatively, the cooling agent source may supply a cooling agent for a predetermined duration of time. The cooling agent may be carbon dioxide or nitrous oxide.

In yet another embodiment of the present disclosure, a method for cooling an end effector assembly having a first jaw member and a second jaw member having a channel defined therein coupled to a cooling agent source and at least one venting port defined therein fluidly coupled to the channel may be provided. The method may include supplying a cooling agent to the channel from the cooling agent source and terminating supply of the cooling agent from the cooling agent source. The cooling agent may be vented into the atmosphere via the at least one venting port.

The cooling agent may be supplied to the channel for a predetermined duration of time where the predetermined duration of time may be determined by measuring a temperature of the second jaw member before the supplying the cooling agent to the channel.

In yet another embodiment, the temperature of the second jaw member may be measured after the cooling agent is supplied to the channel and when the second jaw member reaches a desired temperature, the supply of the cooling agent from the cooling agent source is terminated.

BRIEF DESCRIPTION OF THE DRAWINGS

Objects and features of the presently disclosed systems and methods will become apparent to those of ordinary skill in the art when descriptions of various embodiments thereof are read with reference to the accompanying drawings, of which:

FIG. 1A is a right, perspective view of an endoscopic bipolar forceps having a housing, a shaft and a pair of jaw members affixed to a distal end thereof, the jaw members including an electrode assembly disposed therebetween;

FIG. 1B is a left, perspective view of an open bipolar forceps showing a pair of first and second shafts each having a jaw member affixed to a distal end thereof with an electrode assembly disposed therebetween;

FIG. 2 is a schematic view of an endoscopic bipolar forceps according to an embodiment of the present disclosure;

FIG. 3 is an enlarged view of the area of detail of FIG. 2 showing an end effector assembly according to an embodiment of the present disclosure; and

FIG. 4 is a chart depicting the temporal dependence of tissue temperature during a sealing cycle.

DETAILED DESCRIPTION

Particular embodiments of the present disclosure are described hereinbelow with reference to the accompanying drawings; however, the disclosed embodiments are merely examples of the disclosure and may be embodied in various forms. Well-known functions or constructions are not described in detail to avoid obscuring the present disclosure in unnecessary detail. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present disclosure in virtually any appropriately detailed structure. Like reference numerals may refer to similar or identical elements throughout the description of the figures.

Electromagnetic energy is generally classified by increasing frequency or decreasing wavelength into radio waves, microwaves, infrared, visible light, ultraviolet, X-rays and gamma-rays. As used herein, the term “microwave” generally refers to electromagnetic waves in the frequency range of 300 megahertz (MHz) (3×10⁸ cycles/second) to 300 gigahertz (GHz) (3×10¹¹ cycles/second). As used herein, the term “RF” generally refers to electromagnetic waves having a lower frequency than microwaves. The terms “tissue” and “vessel” may be used interchangeably since it is believed that the present disclosure may be employed to seal and cut tissue or seal and cut vessels utilizing the same principles described herein.

As will be described in more detail below with reference to the accompanying figures, the present disclosure is directed to the use of an active cooling system to cool at least one of the jaw members at the end of the sealing cycle. Active cooling of the jaw members may shorten the sealing cycle, thereby reducing the total operation time.

Referring now to FIGS. 1A and 1B, FIG. 1A depicts a bipolar forceps 10 for use in connection with endoscopic surgical procedures and FIG. 1B depicts an open forceps 100 contemplated for use in connection with traditional open surgical procedures. For the purposes herein, either an endoscopic instrument or an open instrument may be utilized with the electrode assembly described herein. Different electrical and mechanical connections and considerations may apply to each particular type of instrument; however, the aspects with respect to the electrode assembly and its operating characteristics remain generally consistent with respect to both the open or endoscopic designs.

FIG. 1A shows a bipolar forceps 10 for use with various endoscopic surgical procedures and generally includes a housing 20, a handle assembly 30, a rotating assembly 80, a switch assembly 70 and an electrode assembly 105 having opposing jaw members 110 and 120 that mutually cooperate to grasp, seal and divide tubular vessels and vascular tissue. The jaw members 110 and 120 are connected about pivot pin 19, which allows the jaw members 110 and 120 to pivot relative to one another from the first to second positions for treating tissue. More particularly, forceps 10 includes a shaft 12 that has a distal end 16 dimensioned to mechanically engage the electrode assembly 105 and a proximal end 14 that mechanically engages the housing 20. The shaft 12 may include one or more known mechanically-engaging components that are designed to securely receive and engage the electrode assembly 105 such that the jaw members 110 and 120 are pivotable relative to one another to engage and grasp tissue therebetween.

The proximal end 14 of shaft 12 mechanically engages the rotating assembly 80 to facilitate rotation of the electrode assembly 105. In the drawings and in the descriptions that follow, the term “proximal”, as is traditional, will refer to the end of the forceps 10 that is closer to the user, while the term “distal” will refer to the end that is further from the user. Details relating to the mechanically cooperating components of the shaft 12 and the rotating assembly 80 are described in commonly-owned U.S. patent application Ser. No. 10/460,926, now U.S. Pat. No. 7,156,846, entitled “VESSEL SEALER AND DIVIDER FOR USE WITH SMALL TROCARS AND CANNULAS” filed on Jun. 13, 2003.

Handle assembly 30 includes a fixed handle 50 and a movable handle 40. Fixed handle 50 is integrally associated with housing 20 and handle 40 is movable relative to fixed handle 50 to actuate the opposing jaw members 110 and 120 of the electrode assembly 105 as explained in more detail below. Movable handle 40 and switch assembly 70 are of unitary construction and are operatively connected to the housing 20 and the fixed handle 50 during the assembly process. Housing 20 is constructed from two component halves 20 a and 20 b, which are assembled about the proximal end of shaft 12 during assembly. Switch assembly is configured to selectively provide electrical energy to the electrode assembly 105.

As mentioned above, electrode assembly 105 is attached to the distal end 16 of shaft 12 and includes the opposing jaw members 110 and 120. Movable handle 40 of handle assembly 30 imparts movement of the jaw members 110 and 120 from an open position wherein the jaw members 110 and 120 are disposed in spaced relation relative to one another, to a clamping or closed position wherein the jaw members 110 and 120 cooperate to grasp tissue therebetween.

Referring now to FIG. 1B, an open forceps 100 includes a pair of elongated shaft portions 112 a and 112 b each having a proximal end 114 a and 114 b, respectively, and a distal end 116 a and 116 b, respectively. The forceps 100 includes jaw members 120 and 110 that attach to distal ends 116 a and 116 b of shafts 112 a and 112 b, respectively. The jaw members 110 and 120 are connected about pivot pin 119, which allows the jaw members 110 and 120 to pivot relative to one another from the first to second positions for treating tissue. The electrode assembly 105 is connected to opposing jaw members 110 and 120 and may include electrical connections through or around the pivot pin 119. Examples of various electrical connections to the jaw members are shown in commonly-owned U.S. patent application Ser. Nos. 10/474,170, 10/284,562 10/472,295, 10/116,944 and 10/179,863, now U.S. Pat. Nos. 7,582,087, 7,267,677, 7,101,372, 7,083,618 and 7,101,371 respectively.

Each shaft 112 a and 112 b includes a handle 117 a and 117 b disposed at the proximal end 114 a and 114 b thereof that each define a finger hole 118 a and 118 b, respectively, therethrough for receiving a finger of the user. As can be appreciated, finger holes 118 a and 118 b facilitate movement of the shafts 112 a and 112 b relative to one another, which, in turn, pivot the jaw members 110 and 120 from the open position wherein the jaw members 110 and 120 are disposed in spaced relation relative to one another to the clamping or closed position wherein the jaw members 110 and 120 cooperate to grasp tissue therebetween. A ratchet 130 may be included for selectively locking the jaw members 110 and 120 relative to one another at various positions during pivoting.

More particularly, the ratchet 130 includes a first mechanical interface 130 a associated with shaft 112 a and a second mating mechanical interface associated with shaft 112 b. Each position associated with the cooperating ratchet interfaces 130 a and 130 b holds a specific, i.e., constant, strain energy in the shaft members 112 a and 112 b, which, in turn, transmits a specific closing force to the jaw members 110 and 120. The ratchet 130 may include graduations or other visual markings that enable the user to easily and quickly ascertain and control the amount of closure force desired between the jaw members 110 and 120.

As best seen in FIG. 1B, forceps 100 also includes an electrical interface or plug 200 that connects the forceps 100 to a source of electrosurgical energy, e.g., an electrosurgical generator similar to generator 500 shown in FIG. 1A. Plug 200 includes at least two prong members 202 a and 202 b that are dimensioned to mechanically and electrically connect the forceps 100 to the electrosurgical generator 500 (See FIG. 1A). An electrical cable 210 extends from the plug 200 and securely connects the cable 210 to the forceps 100. Cable 210 is internally divided within the shaft 112 b to transmit electrosurgical energy through various electrical feed paths to the electrode assembly 105.

One of the shafts, e.g. 112 b, includes a proximal shaft connector/flange 140 that is designed to connect the forceps 100 to a source of electrosurgical energy such as an electrosurgical generator 500. More particularly, flange 140 mechanically secures electrosurgical cable 210 to the forceps 100 such that the user may selectively apply electrosurgical energy as needed.

As will be described in more detail below, bipolar forceps 10 and open forceps 100 actively cool at least one of the jaw members, e.g., jaw member 304, using a gas cooling agent. The gas cooling agent may be carbon dioxide (CO₂) or nitrous oxide (N₂O) which are non-flammable and neutral with regard to surrounding tissue. The cooling agent may be stored in liquid form in a pressurized reservoir which may be an external reservoir 205 (FIG. 1B) or an internal reservoir 305 (FIG. 2). The flow of cooling agent may be controlled by a valve 207 (FIG. 1B) or valve 307 (FIG. 2).

FIGS. 2 and 3 show a schematic view of a bipolar forceps shown generally as forceps 300. Forceps 300 includes a handle 301, a shaft 302, and two jaw members 303 and 304. The handle 301 includes a reservoir 305 defined therein that houses a liquefied gas cooling agent. The reservoir is hermetically connected to jaw members 303 and 304 by conduit 306. Jaw member 304 has a channel 313, which is coupled, either directly or indirectly, to conduit 306 (FIG. 3). Jaw member 304 also has a plurality of venting ports 312. End 314 of each venting port 312 is in fluid communication with conduit 306 via channel 313. The other end of each venting port 312 has a nozzle 315. Nozzles 315 are open to the surrounding atmosphere. In an embodiment of the present disclosure, nozzle 315 may have a substantially conical shape. Alternatively, a channel (not shown) may be provided instead of nozzle 315 that would have a complex shape that allows for gas expansion. Such channel may venting port the cooling agent into the atmosphere or a condensing cavity.

Valve 307 controls the flow of cooling agent from reservoir 305 to jaw member 304. During the sealing cycle, when electrical sealing current stops, the generator 500 (FIG. 1A) sends a signal and opens valve 307 for a period of time. During this time a portion of cooling agent travels to channel 313 in jaw member 304. As the cooling agent passes through nozzle 315 and is vented into the atmosphere, the cooling agent rapidly expands and the cooling agent's temperature drops, thereby cooling jaw member 304. Cooling is completed when the supply of cooling agent is terminated by closing valve 307. This process may be automated by the generator or may be manually actuated by the surgeon.

There are several possible approaches to determine the period of time that valve 307 remains open. In one embodiment, it depends on how precisely the final temperature should be controlled in order to provide a requisite sealing quality. In particular, valve 307 may be closed after a certain volume of cooling agent is released from reservoir 305. This can be achieved by opening valve 307 for a predetermined period of time.

Alternatively, a temperature sensor 320 disposed on jaw member 304 may be used to determine the duration of the period of time. For instance, temperature sensor 320 may detect the temperature of jaw member 304 and, when the sensor 320 detects a desired temperature, sensor 320 transmits a signal directly to valve 307 or indirectly to valve 307 via generator 500 to close valve 307. In addition, the temperature of jaw member 304 may be measured before cooling and according to the measured temperature the necessary amount of cooling agent and corresponding time of a valve open state may be determined by generator 500, which would then control valve 307 accordingly.

Although FIG. 3 shows a channel 313, venting ports 312 and temperature sensor 320 in jaw member 304, they may be disposed in either jaw member 303 or 304 or in both jaw members.

FIG. 4 depicts an example graph representing the temperature of a jaw member during a sealing cycle according to an embodiment of the present disclosure. When the sealing cycle is activated at time=0 seconds, the temperature of a jaw member is increased until electrosurgical energy is no longer supplied to the jaw member at point 402 (e.g., time=5 seconds). During passive cooling, as represented by line 404, the jaw member cools at a steady rate which is determined by environmental factors such as ambient temperature and the material that composes the jaw members. In active cooling, according to the teachings of the present disclosure, as shown by line 406, the temperature of the jaw members cools much faster than in passive cooling as shown by the high initial slope of line 406.

While several embodiments of the disclosure have been shown in the drawings and/or discussed herein, it is not intended that the disclosure be limited thereto, as it is intended that the disclosure be as broad in scope as the art will allow and that the specification be read likewise. Therefore, the above description should not be construed as limiting, but merely as exemplifications of particular embodiments. The claims can encompass embodiments in hardware, software, or a combination thereof. Those skilled in the art will envision other modifications within the scope and spirit of the claims appended hereto. 

1. An end effector assembly, comprising: a first jaw member; a second jaw member including: a channel defined therein and coupled to a cooling agent source; at least one venting port defined therein and fluidly coupled to the channel, wherein the cooling agent source is configured to supply a cooling agent to the channel and the cooling agent is vented into the atmosphere.
 2. The end effector assembly of claim 1, wherein the second jaw member further includes a temperature sensor configured to detect a temperature of the second jaw member.
 3. The end effector assembly of claim 1, wherein the cooling agent is carbon dioxide.
 4. The end effector assembly of claim 1, wherein the cooling agent is nitrous oxide.
 5. An electrosurgical instrument, comprising: a housing having a cooling agent source and a valve configured to control the supply of cooling agent from the cooling agent source; and an end effector assembly including: a first jaw member; a second jaw member including: a channel defined therein and fluidly coupled to the cooling agent source; at least one venting port defined therein and fluidly coupled to the channel, wherein the cooling agent source is configured to supply the cooling agent to the channel.
 6. The electrosurgical instrument of claim 5, wherein the second jaw member further includes a temperature sensor configured to detect a temperature of the second jaw member.
 7. The electrosurgical instrument of claim 5, wherein the cooling agent is carbon dioxide.
 8. The electrosurgical instrument of claim 5, wherein the cooling agent is nitrous oxide.
 9. A method for cooling an end effector assembly having a first jaw member and a second jaw member having a channel defined therein coupled to a cooling agent source and at least one venting port defined therein fluidly coupled to the channel, the method comprising: supplying a cooling agent to the channel from the cooling agent source; terminating supply of the cooling agent from the cooling agent source; and venting the cooling agent into the atmosphere via the at least one venting port.
 10. The method of claim 9, wherein the cooling agent is supplied to the channel for a predetermined duration of time.
 11. The method of claim 10, further comprising measuring a temperature of the second jaw member before the supplying the cooling agent to the channel, wherein the measured temperature of the second jaw member determines the predetermined duration of time.
 12. The method of claim 9, further comprising measuring a temperature of the second jaw member after the cooling agent is supplied to the channel, wherein when the second jaw member reaches a desired temperature, supply of the cooling agent from the cooling agent source is terminated. 